Chemical Constituents of Living Cells

The biosphere consists of a variety of living organisms. Every living organism is made of chemical constituents- elements, molecules and compounds that support life. Chemical components from both the inorganic and organic worlds are present in nearly the same amounts and perform the same broad duties in all living species, from microorganisms to mammals. Normally, carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur make up more than 99 percent of living cells’ mass. When mixed in various ways, they produce practically all known organic macromolecules. Biomolecules are endogenous, which means they are present and synthesised inside the body. Some are exogenous; they are not present in the body and require them through diet in the form of supplements.

Biomolecules

Biomolecules are those macromolecules and micromolecules that are present in living organisms. They are responsible for all the vital biological processes like morphogenesis, division and development of cells. Biomolecules are essential to the living body; they are the basic constituents of cells. Macromolecules present in the body are carbohydrates, proteins, lipids and nucleic acids. Biomolecules are made up of functional groups. Micromolecules include vitamins, hormones, etc. Most of them are organic, and major constituents include Carbon, Hydrogen, Nitrogen, Oxygen, etc. 

Analysis Of Chemical Constituents

To identify the type, molecular structure, molecular formula and properties of constituent elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur) present in the biomolecule, analysis tests are performed. These techniques also play a crucial role in purifying or separating one element from another.

Steps:

1. A sample piece of living tissue(a vegetable or a piece of liver, etc.) is taken.

2. The tissue is ground and mixed well with trichloroacetic acid (Cl3CCOOH) in mortar and pestle.

3. The thick slurry obtained is then stained through cotton cloth.

4. The products obtained are in the form of acid-soluble frantic(filtrate) and an acid-insoluble fraction(retentate).

5. The filtrate contains biomacromolecules (molecular weight more than 1000 dalton), and retentate contains biomacromolecules (molecular weight less than 1000 dalton) and is then analysed.

Types Of Biomolecules

Types Of Biomicromolecules

Amino Acids

The structure of amino acids consists of an amino group(-NH2), carboxylic group(-COOH), hydrogen(H) and a variable group(R). The carbon to which all the groups are attached is called α- carbon. The structure of amino changes with pH occurs in the form of zwitterion. Amino acids are monomers of protein molecules, and 20 types of amino acids are used for protein synthesis. 

Lipids

Lipids are hydrophobic and are basic constituents of the cell membrane. Lipids can be simple, compound and derived. Basic constituents are Carbon, Hydrogen and oxygen. Fatty acids act as basic constituent units of lipids.

Sugars

Sugars are sweet in taste and hydrophilic carbohydrates. They are formed of 

C, H and O in the ratio of 1:2:1.They are also known as monosaccharides.

Nitrogen bases

These are the nitrogen-containing cyclic compounds found in nucleic acids. There are two types:

a. Purines: Includes Adenine(A) & Guanine(G).

b. Pyrimidines: Includes Cytosine(C), Thymine(T) & Uracil (U)

Types Of Biomacromolecules

Polysaccharides or Complex Carbohydrate

Polysaccharides are polymers of monosaccharides(sugars). Example- Starch, Cellulose, Glycogen. The monomers are joined together by glycosidic bonds.

Protein

Proteins are heteropolymers of amino acids. Several polypeptides are linked together through peptide bonds that make up the protein structure. Polypeptides are linear chains made of amino acids. A peptide bond is formed between 2 amino acids when a carboxylic group of one amino acid is bonded with an amino group of another amino acid, releasing a molecule of water.

Function:

• Support growth and metabolism.

• Acts as an intracellular ground substance.

• Act as receptors.

• Act as hormones.

• Act as enzymes.

• Helps in the transport of nutrients across cell membranes and inside cells.

Nucleic Acids

Nucleic acids are of two types- DNA and RNA. They act as genetic material.

DNA is made of two polynucleotide strands arranged in an antiparallel manner forming a double helix. The two DNA strands are joined together by hydrogen bonds. A nucleotide group consists of a nitrogen base, sugar and phosphate group. DNA is the genetic material found in most organisms.RNA is less stable than DNA and acts as genetic material only in some viruses.

Conclusion

Biomolecules act as basic constituents of building blocks that, in turn, are responsible for the formation of a vast number of living cells, tissues, and organs. The major two categories include biomacromolecules and biomicromolecules. By analysing living tissue (plant tissue/animal tissue), its chemical composition can be determined.